Each of a Patent Literature 1 and a Patent Literature 2 discloses an electrical power system that has an electrical power source; a load; a plurality of converters that are electrically connected in parallel between the electrical power source and the load; and a plurality of control apparatuses (these correspond to controlling units in the Patent Literature 1 or driving circuits in the Patent Literature 2) that are configured to control the plurality of converters, respectively. Each of the plurality of converters includes a plurality of switching elements each of which is referred to as an upper arm or a lower arm. Each of the plurality of converters is configured to switch the upper arm and the lower arm in a complementary manner (namely, to repeatedly turn on and then turn off the upper arm and the lower arm alternately) to boost electrical voltage outputted from the electrical power source and then output the boosted electrical voltage to the load.